JP3063971B2 - Injection device and injection method for inkjet printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ejecting apparatus and an ejecting method for an ink jet printer, and more particularly to a method of heating a heater section by electric energy transmitted to an individual electrode, and forming a thin film using a liquid thermally expanded by the heat. The present invention relates to an ejecting apparatus and an ejecting method of an ink jet printer for causing ink to flow to a medium by flowing the thin film.

[0002]

2. Description of the Related Art First, the configuration and operation principle of a general inkjet printer will be described with reference to FIG.

As shown in FIG. 1, a CPU 10 receives a predetermined print signal from a computer (not shown) via a printer interface and stores an initial set value required for a print operation and a data value required for a system operation. EPRO
The system program in M11 is read, interpreted and executed, and a control signal required for a printing operation is output according to the contents of the program. The ROM 12 stores programs necessary for control and a large number of fonts.
13 temporarily stores data during system operation. Most logic circuits necessary for control of the CPU 10 are embodied in the ASIC circuit section 20, and execute data transmission between the CPU 10 and the peripheral function section. The head driver 30 is a CPU 1 transmitted from the ASIC circuit 20.
The main motor driver 40 controls the driving of the ink cartridge 31 according to the control signal of 0, and functions to prevent the nozzle portion of the ink cartridge 31 from being exposed to air by driving the main motor 41. The carriage motor drive circuit 50 controls the operation of the carriage return drive motor 51, and the line feed drive circuit 60 mainly drives a line feed motor 61 so as to feed and discharge paper by mainly using a stepping motor. Controlling.

A print signal input from a computer to a printer through a printer interface is transmitted to a CPU 10.
Motor drivers 40, 50, 60 according to the control signal of
The print is performed by driving such as. At this time, the ink cartridge 31 employs a method of forming dots by ejecting fine ink droplets from nozzles having a large number of openings.

Next, the structure of the ink cartridge 31 for forming ink droplets will be described in more detail.

FIG. 5 is a cross-sectional view showing the structure of the ink cartridge. In the case 1 forming the outer surface of the container,
The ink 2 sucked into the sponge is stored, and an ink ejecting unit 3 is formed below the sponge.

FIG. 6 is an enlarged sectional view of the ink ejecting section shown in FIG. As shown in the figure, a filter 32 for removing impurities mixed in the ink is provided in the ink ejecting section.
An ink standby chamber 33 for storing the ink filtered by the filter 32; an ink via 34 for supplying the ink in the ink standby chamber 33 to a chip 35 having an ink heater and an ink chamber; The nozzle plate 36 is provided with a plurality of openings for ejecting the ink of the heater (not shown) transmitted from the heater 34 to the medium.

FIG. 7 is a plan cross-sectional view of the ink ejecting section shown in FIG. In the drawing, ink is supplied from an ink via 34 to an ink chamber 37 formed between a nozzle plate 36 having a large number of openings and a chip 35 via a plurality of ink channels 37. In the ink chamber 37,
Electric energy is supplied via the electric connection means 38, and ink droplets are ejected as appropriate according to the control signal.

FIG. 8 is a view showing the FF of the ink ejecting section shown in FIG.
It is the expanded sectional view which looked at the axis | shaft from the B side. As shown in the figure, an oxide film (SiO ₂ ) 102 is formed on a silicon (Si) substrate 101 by an oxide film treatment, and a register layer 103 which generates heat by supplying electric energy is formed on the oxide film 102. The first and second electrodes 104a and 104b are formed on the register layer 103. Furthermore, a protective layer 106 having a multilayer structure is formed so as to cover the first and second electrodes 104 a and 104 b and the register layer 103.
Is formed, and the first and second electrodes 104a and 104b and the register layer 103 are in direct contact with the ink to protect them from being corroded or deformed by a chemical change. Then, an ink chamber 107 is formed above the protective layer 106, and the ink inside the ink chamber 107 generates bubbles by heat transfer from the heater unit 105. In addition, this ink chamber 10
7, an ink channel 108 for supplying ink from the ink via 34 (FIG. 7) communicates. The flow path of the ink channel 108 is defined by an ink barrier 109 formed on the protective layer 106. A nozzle plate 111 having a large number of openings 110 is formed above the ink chamber 107.
From 0, the ejected ink is ejected according to the volume change due to bubbles generated in the ink chamber 107.

The nozzle plate 111 and the heater 105 are arranged at a predetermined distance so as not to interfere with each other. In addition, the pair of electrodes 104a and 104b
It is connected to a terminal bumper (not shown) so that electric energy can be supplied from the outside. A signal is appropriately sent from the head control unit to the terminal bumper, and ink can be ejected from a nozzle opening at a desired position.

Next, the ejection method of the conventional ink ejection device having the above-described configuration will be described with reference to FIG. First, when a print command is received from a computer (not shown) via a printer interface, the CPU 10 sends a corresponding control command to the head driver 30 to supply electrical energy to the pair of electrodes 104a and 104b at positions where printing is desired. I do. As a result, the heater section 105 generates electric resistance heat, that is, P = I ² R, and generates heat corresponding to Joule heat for a certain time. Thus, for example,
The surface of the heater unit 105 is heated to approximately 500 ° C. to 550 ° C., and the heat is transmitted to the plurality of protective layers 106 on the upper side.

Then, the heat is further transmitted to the ink which is mutually wetted with the protective layer 106. At this time, the vapor pressure and the distribution C of the vapor pressure bubbles in the heater section 105 are changed as shown in FIG. , The center of the heater section 105 appears at its highest point with the center of symmetry as the axis of symmetry. In this way, the ink is heated by the heat transfer to form a vapor pressure bubble, and the vapor pressure bubble causes a volume change in the ink above the heater unit 105. Then, the ink is pushed out from the opening 110 of the nozzle plate 111 to the outside due to the volume change.

At this point, the two electrodes 104a, 104
When the supply of the electric energy to b is cut off, the heater unit 105 is instantaneously cooled, the expanded vapor pressure bubble contracts, and the ink is restored to the normal state accordingly. However, the ink that has been expanded and pushed out of the nozzle plate through the opening forms an ink droplet by the action of surface tension or the like, and is ejected toward a print medium such as paper to form a desired image. As a result, the internal pressure drops by a volume corresponding to the ejected ink, and new ink is refilled from the ink reservoir via the ink via.

Here, the above-described conventional ejection method using the ink ejection device has the following problems.

First, since bubbles are formed by using high heat to eject ink, a thermal change occurs in the ink components, and the internal life of the element is shortened by a shock wave caused by the bubbles, and the printing quality is reduced. Deterioration sometimes occurred. This has been a source of frustration for users seeking high quality printing.

Second, since the ink, the register layer 103, and the pair of electrodes 104a, 104b are joined using the protective layer 106 as an intermediate medium, they react electrically with each other, and the heater 105 and the two electrodes 104, 104 are connected. Corrosion occurred due to the mutual movement of ions in the boundary layer of ', and the life of the head was sometimes shortened.

Third, since bubbles are generated in the ink barrier containing the ink, the impact of the bubbles increases the cycle time for refilling the ink.

Fourth, since the shape, rectilinearity, circularity, and uniformity of the droplet volume of the ink droplet depend on the shape of the bubble formed indefinitely, depending on the formation of the bubble,
Print quality was sometimes affected.

In order to solve such a problem, an improved injection system using an injection device is disclosed in US Pat. No. 4,480,2.
No. 59, this injection device will be briefly described below with reference to FIG. FIG.
As shown in FIG. 7, the nozzle plate 206 is provided with an opening 206a functioning as an orifice for ejecting ink. On the opposite side of the nozzle plate 206, a flexible thin film 204 of rubber silicon material is formed, and together with the ink barrier 205, forms an ink chamber 207 as a space for temporarily storing ink. Under the thin film 204, two electrodes 202a and 202b and a resistor 203 are arranged. Note that the resistor 203 is disposed so as to be sandwiched between the two electrodes 202a and 202b.

On the other hand, a predetermined liquid is supplied to the second space 208 formed by the surface roughness between the surface of the thin film 204 and the surface of the resistor 203 by using a capillary phenomenon. Electrode 202
The voltage pulse transmitted to the resistor 203 by a and 202b heats and evaporates the liquid in the second space 208. As a result, the thin film 20 which is a flexible elastic body is
4 is deformed. Due to the deformation of the thin film 204, a volume change occurs in the ink chamber 207 above the thin film 204. Then, due to this volume change, the ink in the ink chamber 207 is ejected to the outside from the opening 206a forming a nozzle.

In the above-described ejection apparatus, the ejection of the ink is not caused by the thermal deformation of the thin film 204 but is caused by the resistance 203 and the thin film 2.
In the state where the two surfaces of the thin film 204 are in direct contact with each other, the thin film 204 is elastically deformed due to the vapor pressure bubbles of the liquid flowing into the second space 208 formed by the surface roughness.

[0022]

However, in the improved injection device described above, the thermal conductivity is low because the thin film 204 is made of flexible rubber silicon. Therefore, heat is not effectively dissipated, and it takes a long time to return to the original state after the expansion, and the ink supply speed is correspondingly reduced, which causes a problem that the print speed is reduced as a whole. Was.

[0023]

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of the above-described conventional ejection apparatus and ejection method of an ink-jet printer. A new and improved inkjet printer that uses a thin film that is a substance and separates the heating resistance and the insulating barrier by using the thin film can improve the ink ejection speed. An object of the present invention is to provide an injection device and an injection method.

[0024]

According to a first aspect of the present invention, to solve the above-mentioned problems, the volume of ink in an ink chamber is controlled by the heat transfer from a heater that generates heat by supplying electric energy. A change is caused to push out the ink droplet from the opening of the ink chamber, and the power to the heater is
An ejection device for an ink jet printer is provided, which is configured to eject an ink droplet by a change in volume in an ink chamber due to interruption of gas energy . And
According to the first aspect of the present invention, the injection device of the ink jet printer is capable of thermally expanding by heat transfer from the heater.
A heating chamber in which a functional fluid is stored;
Separating the heating chamber from the heating chamber
And heat transmitted from the heater section via the fluid.
More deformed, causing a volume change in the ink chamber.
A thin film having thermal expansion and flexibility,
It is provided on the heater side of the chamber . According to this configuration, the fluid in the heating chamber thermally expands due to the heat generated by the heater section, deforming the thin film, causing a volume change in the ink in the ink chamber, and ejecting ink droplets by buckling.

Further, it is preferable that the fluid in the heating chamber is a fluorine compound having high heat conductivity.

Further, it is preferable that the thin film is configured such that one surface seals the heating chamber and the other surface is in contact with the ink in the ink chamber.

Still further, by interrupting the electric energy to the heater section, the heat transfer from the heating chamber is interrupted and the thin film cooled by the ink in the ink chamber is cut off. It is preferable that a pressure drop is generated in the ink chamber by moving the ink chamber to the heating chamber side, and a new ink is supplied into the ink chamber by the pressure drop.

Further, it is preferable that the inlet for injecting the fluid into the heating chamber is sealed by a thin film.

Further, as described in claim 6, the portion in contact with the ink in the ink chamber and the portion in contact with the heating chamber have a difference in shrinkage rate with respect to a change in heat, and the difference due to the interruption of heat transfer. It is preferable to use a thin film that deforms with elastic force in the direction of the heating chamber rapidly within a certain range due to inertial force during cooling.

Further, according to a seventh aspect, A
g, Al, Cd, Cs, K, Li, Mg, Mn, Na,
A thin film made of a composite material containing one or more materials selected from the group consisting of Zn may be used.

Further, a thin film composed of a synthetic material of a metal and an organic substance may be used.

Furthermore, the fluid in the heating chamber can be a liquid, a gas, or a mixture of a liquid and a gas, as described in the ninth aspect.

In order to solve the above-mentioned problems, the second aspect of the present invention
According to the aspect of the invention, the volume of the ink in the ink chamber is changed by the heat transfer from the heater unit that generates heat by the supply of electric energy, the ink is pushed out from the opening of the ink chamber, and the electric power to the heater unit is changed. Supply of energy
An ink jet printer ejecting method for ejecting ink droplets by a change in volume in an ink chamber due to interruption of supply is provided. According to the ink jet printer of the present invention, the ink chamber is divided into a first chamber on the opening side and a second chamber on the heater side by a thin film having thermal expansion and flexibility. And second
Storing a fluid to be thermally expanded by heat transfer from the heater portion in the chamber, by the fluid heating or cooling by the heater unit, via the front thermal expansion and the fluid of said fluid
The thin film deformed by heat transmitted from the heater unit
A volume change is caused in the ink chamber via the opening, and an ink droplet is ejected from the opening according to the volume change.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of an ejection apparatus and an ejection method of an ink-jet printer configured based on the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an enlarged sectional view of a preferred embodiment of the injection device according to the present invention. Note that, in this specification, components having the same functional configuration are assigned the same reference numerals, and redundant description will be omitted.

As shown in FIG. 1, an oxide film (SiO ₂ ) 12 is formed on a silicon (Si) substrate layer 11 by an oxide film treatment.
Is formed, and a register layer 13 is further formed thereon. On the resistor layer 13, electrodes 14 capable of supplying electric energy of different polarities to each electrode in pairs are provided.
a, 14b. The register layer 13 generates heat when electric energy is supplied through these electrodes 14a and 14b, and forms a heater section 15 together with a protective layer 16 formed on the upper side. The protective layer 16 is a multi-layer protective layer that covers the register layer 13 and the protective layer 16 and prevents their surfaces from being corroded or deformed by oxidative contact with air. Further, an insulating layer 22 that covers a part of the protective layer 16 and forms a certain space that forms a heating chamber 23 over the heater unit 15 is disposed above the protective layer 16. The heating chamber 23 forms a closed space by the flexible thin film 24. An ink barrier 19 is disposed on the thin film 24, and the ink barrier 19 forms an ink chamber 17 above the heating chamber 23. Further, an ink plate 21 having an opening 20 at a position corresponding to the ink chamber 17 is disposed above the ink barrier 19.

With this configuration, the fluid (including liquid and gas) filled in the heating chamber 23 is supplied to the heater 1
By causing thermal expansion due to the heat generated from 5 and generating a vapor pressure valve, the flexible thin film 24 at a portion corresponding to the ink chamber 17 is bent, and furthermore, the flexible thin film 24 is formed in the ink chamber 17 as described later. By causing a volume change, predetermined ink can be ejected from the opening 20 of the nozzle plate 21. The ink barrier 19
Defines a flow path of an ink channel (not shown) that forms a supply path of ink supplied from an ink via (not shown). Further, the pair of electrodes 14 a and 14 b are configured to be able to supply electric energy of different polarities through the electric connector means 25.

The thin film 24 is made of, for example, Ag, Al, Cd,
It can be composed of a thin film containing a material such as Cs, K, Li, Mg, Mn, Na and Zn. In some cases, the durability can be extended by using a synthetic material of the metal material and another organic material.

As the liquid to be filled in the heating chamber 23, a solution such as a fluorine compound having a high vapor pressure and excellent heat conductivity can be used. An inlet (not shown) for injecting a liquid is formed in the heating chamber 23, and a thin film is stuck so as to seal the inlet.

As described above, according to the ejecting apparatus according to the present embodiment, the regions (hereinafter referred to as the ink chambers) corresponding to the ink chambers 107 and 207 of the conventional ejecting apparatus described with reference to FIGS. The ink chamber 17 and the heating chamber 13 through the thin film 24.
It is configured separately. By separating the ink chamber region using the thin film 24 as described above, the problem of the conventional method in which the ink is heated by the heater unit 105 is solved. That is, through the heating chamber 23 filled with the predetermined fluid as described above, corrosion caused by direct contact between the ink in the ink chamber 17 and the heater unit 15 is prevented, and the ink after the vapor pressure is generated is formed. The heater section 15 can be effectively protected from the impact due to the injection.

Next, the operation of the ejection device of the ink jet printer according to the present embodiment having the above configuration will be described with reference to FIGS.

First, FIG. 2 shows two electrodes 14a and 14a.
The state when power is applied to b is shown. In order to form a print at a desired position, that is, a position set for printing, a head driver (not shown) supplies electric energy to the corresponding electrode as an electric signal. That is, the electrical connectors 25 corresponding to the two corresponding electrodes 14a, 14b are made conductive, and the two electrodes 14a, 14b are turned on.
b) are supplied with electric energy of different polarities.

The heater section 15 generates heat by the supplied electric energy, and the heat passes through the fluid in the heating chamber 23 and the thin film 24 made of a metal composite material having high thermal expansion.
Is transmitted to Thus, the thin film expands in the longitudinal direction, and the vapor pressure thermally expanded in the closed space in the heating chamber 23 deflects the thin film 114 so as to push the thin film 114 toward the ink chamber 19. As a result, the ink in the ink chamber 17 is pushed out toward the opening 20 formed in the nozzle plate 11 by the pressing force of the thin film 24. That is, the liquid and gas in the heating chamber 113 expand due to heat, and the pressure (P1) becomes larger than the initial pressure (P0), that is, the pressure when power is not applied. It is extruded in 17 directions.

As shown in FIG. 3, the ink droplets pushed out from the opening 20 have two electrodes 14a, 1a.
When the electrical energy supplied to 4b is cut off,
Separated toward a print medium such as paper.

At this time, the thin film 24 having good thermal conductivity is cooled through the ink on the upper portion, and the metal layer on the substrate is placed through the fluid having good thermal conductivity filled in the heating chamber 23. Cooling. At a certain point, the thin film 24 undergoes volume deformation from the ink chamber side to the heating chamber side due to rapid cooling of the heating chamber side. As a result, a suction force is generated in the ink chamber 17, and new ink is supplied via an ink channel (not shown). This is called a buckling phenomenon.

That is, the ink droplets pushed out of the opening 20 by the thin film 24 deformed in accordance with the thermal expansion of the fluid in the heating chamber 23 cut off the electric energy to the two electrodes 14a and 14b, and the accompanying heating. Chamber 13
The opening 1 is repelled by the suction force generated in the ink chamber 17 due to the temperature drop of the ink and the cooling deformation of the thin film 14.
10 and ejected in the direction of the print medium.

Here, the upper part of the thin film 24, that is, the part facing the ink chamber 17 is the ink chamber 1
Since the ink is in contact with the ink inside 7, the heat is easily lost, and the inertial force for returning to the original state is large. On the other hand, the lower part of the thin film 114, that is, the heating chamber 113
The portion facing the side has a relatively small elastic force to return to the original state. This difference is due to the difference in the shrinkage rate with respect to the thermal change between the portion in contact with the ink and the portion in contact with the heating chamber.

Therefore, the pressure (P
2) When the power applied to the two electrodes 14a and 14b is cut off, the initial pressure (P0) of the heating chamber 23 is reduced.
It becomes smaller and rapidly deforms in the opposite direction (toward the heating chamber 23) within a certain range. Further, if the pressure (P2) of the heating chamber 23 at the time of power-off is changed to the initial heating chamber 2
3 (P0), the elastic force of the thin film 24 acts to sharply reverse the direction (heating chamber 2) within a certain range.
(3 directions). With this operation, a suction force is generated in the ink chamber 17, and the ink droplet E pushed out from the opening 20 is separated from the ink in the ink chamber 17 by the action of surface tension or the like, and is ejected toward a print medium such as paper. Is done.

The jetting device and jetting method of the ink jet printer according to the preferred embodiment of the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to this example. It is clear that a person skilled in the art can conceive various changes or modifications within the scope of the technical idea described in the claims, and those modifications naturally fall within the technical scope of the present invention. It is understood to be included.

[0050]

As described above, according to the present invention, the ink and the heater section are interconnected by adjusting the vapor pressure due to the thermal expansion of the liquid in the heating chamber and ejecting the ink by deforming the thin film. To prevent corrosion due to the contact between the ink and the protective film, and to effectively prevent the protective film from being damaged by the impact generated during the bubble jet as in the past. And high quality printing can be ensured.

In addition, the compressive force of the thin film in contact with the ink chamber in the longitudinal direction causes a sudden deformation on the heating chamber side, so that the ink ejection speed is improved.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of an ejection device of an inkjet printer according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an operation state of the ejection device of the inkjet printer according to the present invention.

FIG. 3 is an explanatory diagram illustrating an operation state of the ejection device of the inkjet printer according to the present invention.

FIG. 4 is a block diagram illustrating a schematic configuration of a conventional inkjet printer.

5 is a schematic sectional view of the ink cartridge of the ink jet printer shown in FIG.

FIG. 6 is an enlarged sectional view of a head portion of an ink cartridge of a conventional ink jet printer.

7 is a cross-sectional plan view of the injection device as viewed from the A side with the EE axis of the head portion of FIG. 6 as a cross section.

8 is an enlarged cross-sectional view of the injection device as viewed from the B side with reference to the FF axis of the head unit in FIG. 7;

FIG. 9 is an exemplary view showing an ink ejection method according to the related art.

FIG. 10 is a nozzle plate section of an improved prior art injector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Silicon substrate 12 Oxide film 13 Register layer 14a, 14b Electrode 15 Heater part 16 Protective layer 17 Ink chamber 19 Ink barrier 20 Opening 21 Nozzle plate 22 Insulating layer 23 Heating chamber 24 Thin film 25 Electrical connection device

Claims (10)

(57) [Claims] 1. A extruded ink droplets through the opening of the ink chamber causes a volume change in the ink in the ink chamber by the heat transfer from the heater portion for heating by the supply of electrical energy, electrical energy to the heater unit In an ejection device of an ink-jet printer, which is configured to eject an ink droplet by a change in volume in an ink chamber due to interruption of the ink: a fluid that can be thermally expanded by heat transfer from the heater portion is stored.
A heating chamber which is separated from the ink chamber and the heating chamber;
The thermal expansion of the fluid and transmission from the heater section through the fluid.
Deformed by the heat reached and the volume in the ink chamber
Thermally expandable and flexible thin film that causes change
And. Provided on the heater side of the ink chamber . 2. The apparatus according to claim 1, wherein the fluid in the heating chamber is a fluorine compound having high thermal conductivity. 3. The ink jet printer according to claim 1, wherein one side of the thin film seals the heating chamber and the other side is in contact with the ink in the ink chamber. 4. By interrupting electrical energy to said heater section, heat transfer from said heating chamber is interrupted and said thin film cooled by ink in said ink chamber is moved to said heating chamber side. 4. The method according to claim 1, wherein the pressure drop causes a pressure drop in the ink chamber, and the pressure drop supplies new ink into the ink chamber. Injection device for inkjet printer. 5. An ink jet printer according to claim 1, wherein an inlet for injecting a fluid into the heating chamber is sealed by the thin film. apparatus. 6. The thin film has a difference in shrinkage rate with respect to a change in heat between a portion in contact with the ink in the ink chamber and a portion in contact with the heating chamber. 2. The jetting device of claim 1, wherein the jetting device is elastically deformed toward the heating chamber within a predetermined range by a force. 7. The thin film is made of Ag, Al, Cd, Cs,
7. A composite material comprising one or more materials selected from the group consisting of K, Li, Mg, Mn, Na, Zn, according to claim 1, 2, 3, 4, 5, or 6. An ejection device for an ink jet printer according to any one of the above. 8. The method according to claim 1, wherein the thin film is made of a synthetic material of a metal and an organic substance.
8. The ejection device for an inkjet printer according to any one of 4, 5, 6, and 7. 9. The method of claim 1, wherein the fluid in the heating chamber is a liquid, a gas, or a mixture of a liquid and a gas.
The ejection device for an ink jet printer according to any one of the above. 10. A heat transfer from a heater unit which generates heat by supply of electric energy causes a change in volume of ink in the ink chamber, thereby pushing out the ink from an opening of the ink chamber and providing electric energy to the heater unit. Companion
A method of ejecting ink droplets by a change in volume in an ink chamber due to interruption of supply is provided in the ink jet printer. The first chamber on the opening side and the heater section are formed by a thin film having thermal expansion and flexibility in the ink chamber. And a fluid that thermally expands due to heat transfer from the heater section is stored in the second chamber, and the fluid is heated or cooled by the heater section, thereby thermally expanding the fluid. And the heater section through the fluid
Through the thin film deformed by the heat transmitted from the
A method for ejecting an ink jet printer, comprising: causing a volume change in the ink chamber; and ejecting an ink droplet from the opening according to the volume change.